Supersonic barrel-fired projectiles carrying propulsion units



&067585 Dec. 31, 1962 G. LUDWIG SUPERSONIC BARREL-FIRED PROJECTILES CARRYING PROPULSION UNITS Filed April 9, 1958 aearaa Patented Dec. lil, 1962 3,067,685 SUPERSONHC BARRELFEED PRGEECTELES CAYING ?RGPULSTQN UNHTS Giinter Ludwig, Kiel, Germany, assignor to Soeiete ciare &Expansion Commerciale et Eudustriele .A.

"Spindexfl arnen, %wit'erland Filed Apr. 9, 1958, Ser. Ne. '727,330 Clams priority, application Germany Apr. 10, 1957 6 Cm'ms. (Ci. 162-925) The present invention relates to a projectile which is to be fired from a barrel at supersonic velocity and which is provided with a propulsion unit that becomes operative after firing. Such a projectile is herein referred to as a supersonic barrel-red projectile carrying a propulsion unit.

With conventional firearms, the projectile has imparted thereto a kinetic energy which enables it to cover the distance to the target against the action of airresistance and gravity. The firing range depends inter alia on the muzzle velocity and the weight of the projectile. With equal muzzle velocities and equal air resistances, a heavy projectile travels further than a light one. The reaction to the acceleration which the projectile is given in the barrel is the recoil of the weapon. With equal muzzle velocities and otherwise equal circumstances, the heavy projectile produces the greater recoil. With conventional firearms, the gases from the powder discharge forwardly. The .gun crew does not have to leave the firing position when the projectile is fired. It is thus possible to etfect rapid reloading and acontinuous feeding of automatic loading devices.

` On account of the high intial supersonic velocity, the fiight of the projectile is stable from the start and thus the accuracy of firing is good. It is however decreased in proportion as the kinetic energy of the projectile is absorbed by the air resistance and thus the accuracy 'in flight decreases. consequently, the time of fiight of the projectile increases relatively quickly as the range becomes longer, so that when firng against moving targets, aim-oil errors occur to an increasing degree as the range increases. Firing becomes pointless when the projectile velocity no longer exceeds the target velocity to a sufficient extent or falls below it. It is clear that only projectiles having a high velocity throughout their fiight, i.e. projectiles with their own propulsion unit (self-propelling projectiles), permit firing against high-speed targets to be effective.

With self-propelling projectiles, the propellant gases are discharged rearwardly. In cases where the projectile is not fired from a barrel so that the propulsion unit must also be responsible for launching the projectile the gun crew must take cover on firing and this has a deleterious efiect on the rate of fire. Such self-propelled projectiles have a low intial velocity and the target accuracy is therefore restricted unless there is remote control of the flight of the projectile. The propulsion units of such self-propelled projectles must not only supply the power for overcoming air resistance and gravity, but also the power for the total intial acceleration upon launching. Furthermore, energy must be supplied suflicient to accelerate the propulsion unit itself and the weight of fuel serving for the acceleration.

Rapid and accurate firing against rapidly moving targets at ranges which are greater than, for example, those of the modern machine guns and automatic guns s only possible if a projectile fired at normal muzzle velocity is given its own propulsion unit which enables the projectile to maintain its muzzle veloity as far as the target or even for this velocity to be increased. The power of the projectile propulsion unit and the weight of fuel to be accelerated in this case only have to be substantially sufiicient in order to overcome the gravity of the earth and air resistance during the time of flight, while the intial acceleration is provided by the gun.

An artillery shell of conventional type is made as heavy as possible, not only for the purpose'of conveying the largest possible amount of explosve to the target, but also for the purpose of enabling the shell to overcome the air resistance by means of its kinetic energy over a long trajectory and in addition to exert an armour-piercing action on hitting the target. If now a self-contained propulsion unit and not the weight of the projectile is used to enable the latter to overcome the air resistance and if other means, for example a hollow charge, is used for the armour-piercing efiect, the ring range and the piercin'g power' place no direct demands on the weight of the projectile. The weight requirement for propellant and hollow charge is smaller than that mass With an oldtype projectilewhich is equivalent in the respects just indicated. consequently, such a projectile can be lighter in weight. With an equal muzzle velocity, the rearward thrust is smaller and the recoil shorter, this always being desirable for example for the weapons used on ships and tanks. Alternatively, with anequalrearward thrust, it is possible to achieve a higher muzzle velocity and thus a greater accuracy in firing.

Experiments with shells having a self-contained propulsion unit have already been carried out.- If the selfcontained propulsion unit is arranged on the base of the shell, the point of application of the forwardly propelling force when the propulsion unit becomes operative is cone sidera'bly behind the centre of gravity of the shell, which centre of gravity can be' considered as the point of application of the forwardly propelling force resulting from the kinetic energy. Thus, these projectile's became unstable in flight when the propulsion unit became operative. On the other hand, projectiles of the type in question have also already been proposed in which the propellant charge for the self-contained propulsion unitthat becomes operative after fir'ing is arranged in the projectile body near thecentre of gravity of the projectile and the gases formed by the burning of thispropellant charge are exhausted through a plurality of rearwardly directed nozzles opening laterally on the projectile body. The effi- Ciency of this self-contained propulsion unit Operating as a rocl et motor with thrust nozzles is however obviously very poor. Moreover, it is only with a relatively large projectile that a sufliciently large combustion chamber and the necessary nozzles with their connecting ducts can be arranged in a satisfactory manner in the projectile body.

According to the present invention there is provided a supersonic barrel-fired projectile, comprising a fusiform projectile body, a nose and a tal on said body, a propellant charge of solid fuel arranged in annular form on the outside of the body in the region of the largest crosssection thereof, and a ring of priming composition, for

igniting the solid fuel, situated on the outside of the body, the distance between said nose and the solid fuel being slightiy greater than the distance between said nose and the priming composition, whereas the distance between said nose and the centre of gravity of the projectile is still greater.

On account of the Construction just indicated, it is possible to dispense with both a separate combustion chamber and thrust nozzles in the projectile body; it thus becomes possible for even small projectiles to be provided with their own propulsion unit in a simple manner and` at relatively low expense. The position of the ignition point which is chosen in this case also guarantee-s that the expansion of the propellant gases takes place wholly or at least partially between the outside wall of the front tapering section of the fusiforrn projectile body and the shock wave emanating during fiight with supersonic velocity from the nose of the projectile. The gas expansion not only has a thrust effect owing to the rearward flow of the gases caused by the high pressure zone in the shock wave, but by Choosing a suitable propellant and quantity thereof, can so' influence the shock wave that the Mach angle of the shock wave is altered to a value corresponding to a smaller projectile velocity. in this way, the resistance opposing the projectile is reduced and the projectile velocity will decrease less rapidly than when a self-contained propulsion unit is not used. The traectory of the projectile thus becomes flatter and longer under the action of theexisting kinetic energy.

For a better understanding of the invention and to show how the same may be carried into eifect, reference will now bcmade to the acconpanying drawing, which shows ,a longitudinal sectional View of a projectile. The illustrated projectile has a nose, a tail and a region of maximum diameter between the nose and the tail at which a propellant fuel is burnt. The surface of the projectile between the region at which the fuel 'is ignited and the tail is completely smooth, that is to say there are no driving bands' or other irregularities in that part of the projectile surface. The centre of gravity of the projectile is on the longitudinal centi-eline of the projectile and between the planes indicated by the references X' and Y, that is to say the centre of gravity is behind the region at which ignition of the fuel takes place but Well forward of the tail. The exact position of the centre of gravity will, of course, depend upon the dimensions of the projectile and the specific gravities of the various parts thereof so that it is not necessary, and would in fact be misleading, to specify the exact position of the centre of gravity in the projectile.

In the drawing, there is shown a fusiform projectile body 1 which must have a thick wall in its rearward portion, especially in the case of fixed gun ammunition, in order to withstand the gas pressure in the barrel. There is provided a driving band 2 for co-operation with the gun barrel rifling to produce rotation of the projectile. 3 is a primer composition which consists of py'otechnic materials and which is initially ignited, upon firing, by the gases from the Cartridge powder and then in its turn ignites solid fuel 4 which serves as propellant .and is arranged. as a ring in an annular recess, which also contains the primer composition on the outside of the body 1. 5 is a tail unit for increasing the stability of the' projectile in fiight. This tail unit is inclined to the direction of flight in order to maintain in flight the rotation produced before the projectile leaves the muzzle. The tail unit can be comparatively small, since it is completely in the flow of the propellant gases. 6 is the explosive charge, which can be of conventional type, and 7 is the cartridge case. It is of course also possible for solid projectiles, for example those of infantry rifles or machine guns, to be equipped with the additonal propulsion' unit previously described ,in order to increase the efficacy of these weapons. The projectile described above is distinguished from the previously known types of projectiles by the fact that ithas the form of a closed solid or hollow body which is tapered towards the front and rear ends, inside which body is a solid core of an explosive charge of molecular type, and on the outside of which is a priming composition situated in the region of the largest cross-section and disposed in front of the centre of gravity of the projectile, while to the rear of this composition, seen in the direction of flight, there is a propellant charge consisting of a solid fuel.

The projectile shown in the drawing is provided at its rearward end with a tail' unit which is disposed in the gas stream of the propulson jet and which serves to stabilise the projectile in flight, such tail unit being so shaped that it imparts a rotation to the projectile.

lt is to be noted that the expression projectile used in the previous description is to cover any body for flight in atmosphere at supersonic velocity.

It will be apparent from the drawing that the ring of priming composition 3 is situated at a location which is on the outside of the projectile body in the region of the greatest diameter thereof. lt is adjacent the solid fuel and is between the latter and the nose of the projectile and closer to said nose than to the tail of the projectile measured along the longitudinal axis of the projectile. The distance between the nose and the solid fuel is therefore sli htly greater than the distance between' the nose and the priming composition, whereas the distance between the nose and the centre of gravity of the projectile is still greater.

I claim:

l. A supersonic barrel-fired projectile, comprising a fusiform projectile body, a nose and a tail on said body, a propellant charge of solid fuel arranged in annular form on the outsideof the body in the region of the largest diameter thereof, and a ring of priming composition, for igniting the solid fuel, situated at a location whichis on the outside of the body in the region of the greatest. diameter thereof and' is adjacent the solid fuel and is between the latter and said nose and Closer to said nose than to said tail, measured along the longitudinal aXis of the projectile. i

2. A projectile according to claim 1, and further comprising wall portions of saidbody dening an annular recessiextending, around the outside of -said body in the region of the greatest diameter thereof, the solid fuel and the priming composition being disposed within said recess.

3, A supersonic barrel-fired projectile, comprisng a fusiform projectile body, a nose and a tail on said body, a propellant charge of solid fuel arranged in annular form on the outside of the body in the region of the largest cross-section thereof, and a ring of priming composition, for ignting the solid fuel, situated on the outside of the body, the distance between said nose and the solid fuel being slightly greater than the distance between said nose and the priming composition, whereas the distance between said nose and the centre of gravity of the projectile is still greater.

4. A supersonic barrel-fired projectile, comprising a fusiform projectile body, a nose and a tail on said body, a propellant charge of *solid fuel arranged in annular form on the outside of the body in the region of the largest cross-section thereof, and a ring of priming composition, for igniting the solid `fuel, situated on the outside of the body, the distance between said nose and the solid fuel being slightly greater than the distance between said nose and the priming composition, whereas the distance between said nose and the centre of gravity of the projectile is still greater, the entire part of the projectile body between the fuel and said tail having a completely smooth external surface.

5. A supersonic barrel-fired projectile, comprising a fusiform projectile body, a nose and a tail on said body a propellant charge of solid fuel arranged in annular form on the outside of the body in the region of the largest diameter thereof, and a ring of priming compo-` sition, for igniting the solid fucl, Situated at a location which is on the outside of the body in the region of the greatest diameter thereof and is adjacent the solid fuel and is between the latter and said nose and closer to said nose than to said tail, measured along the longitudinal axis of the projectile, the entire part of the projectile body 'between the fuel and said tail having a completely smooth external surface.

6. A projectile according to claim 1 and further comprisig wall portons of said body defining an annular recess extending around the outside of said body in the region of the largest cross-section thereof, the solid fuel and the priming composition being disposed within said recess.

References Cited in the file of this patent UNITED STATES PATENTS Semple Aug. 12, 1902 Chilowsky Apr. 26, 1921 Denoix Jan. 31, 1939 Abramson Mar. 9, 1954 FOREIGN PATENTS France Sept. 2, 1920 France June 23. 1954 UNITED STATES PATENT OFFIC TEFECATE er Patent No 3,07,685 December ll, 1962 Gnter Ludwig It is hereby Certified that error appears in the above numbered patent req'ring correction and that the said Letters Patent should read as corrected below.

In the grant; lines 3 and 13 and in the heading to the printed specification, line 6, for Spindex'' each occurrence,

read "Sfirdex" Signed and sealed this 20th day of August l93 (SEAL) Attestz` DAVID L. LADD ERNEST W. SWIDER Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,07,85 December ll, 1962 Gnter Ludwig It is hereby Certified that error appears in the above number-ed patent req'ring correction and that the said Letters Patent should read as corrected below.

In the grant, lines 3 and 13 and in the heading to the printed specification, line 6, for ""Spindex".' each occurrence, read "Sfrdex" Signed and sealed this 20th day of August l93 (SEAL) Attestz' DAVID L. LADD Commissioner of Patents EENEST W. SWIDER Attesting Officer 

